Laser transmitters and other small modern electronic components are widely used today in various applications, such as communications systems. Such components are, for example, typically comprised of at least one semiconductor chip which is soldered to a submount assembly. The solder used to fabricate such components is applied at sufficiently high temperatures that the resulting stress can adversely affect the functionality of the semiconductor chip.
This stress typically results from one of several sources. Either from a mismatch in the temperature coefficients of the semiconductor chip and the submount, or from the solder having a substantially higher melting temperature higher than that at which the chip is used. Alternatively, the stress can result from an improperly formed solder bond between the chip and the submount.
Conventional methods for determining whether an semiconductor chip has been properly soldered to a submount typically involve a crude "push-off" test in which the chip is sheared from the submount. This test, however, suffers from a significant drawback. Specifically, it is always destructive to the chip rendering it inoperable. In addition, this test is often difficult to perform because the chip may shatter rather than detach from the submount. Moreover, the test is often provides inconclusive results when the solder pattern of the detached chip is examined.